1. Field of the Invention
The present invention relates to novel poly(olefin)-polyamine-N-substituted-polycarbamates, their use in preventing deposit formation in engines and to fuel compositions containing these novel poly(olefin)-polyamine-N-substituted-polycarbamates.
2. Background
It is known that during the initial operation of a new or clean internal combustion engine, a gradual increase in octane requirement (OR), i.e., the fuel octane number required for knock-free operation, increases with the buildup of combustion chamber deposits until a stable level is reached which generally corresponds to a time when deposits remain relatively constant. The actual stable level can vary with engine design and even with individual engines of the same design.
Many additives are known which can be added to hydrocarbon fuels to attempt to prevent or reduce deposit formation or remove or modify formed deposits in the combustion chamber and adjacent surfaces, such as valves, ports, and spark plugs, in order to reduce octane requirement.
Continued improvement in design of internal combustion engines, e.g., fuel injection and the like, brings changes to the atmosphere of the combustion chamber so there is a continuing need for new additives to control the problem of deposits and improve drivability which is usually related to deposits.
Additive molecules that liberate carbon dioxide under thermal conditions have been found to aid in the control and/or removal of deposits. U.S. Pat. No. 4,936,868, issued Jun. 26, 1990, discloses the use of certain poly(olefin)-N-substituted-carbamates as a deposit preventing or reducing additive in gasolines. These additive molecules have one carbon dioxide producing carbamate group per molecule. To increase the carbon dioxide producing effect of this additive in a gasoline requires increasing the amount of additive present, which can result in undesired side effects.